Warning to the aracnophobic and the weak in the heart: this is the subject of nightmares, so you may want to continue cautiously.
A team of biologists led by the University of Michigan documented 15 weird and disturbing interactions in predators and prey in the Amazon rainforest, including night-time imaging of a dining-size tarantula that dragged a new fuss to the forest floor.
The photos are part of a new article in the magazine entitled "Ecological interactions between arthropods and small vertebrates in an Amazon rainforest." Arthropods are invertebrate animals with segmented bodies and articulated appendages that include insects, arachnids (spiders, scorpions, mites and mites) and crustaceans.
The article, scheduled for online publication on February 28 at Conservation of amphibians and reptiles, details cases of arthropod predators, mainly large spiders along with a few cents and a giant water error, which prey on vertebrates such as foxes and rapees, lizards, snakes and even a small harrier.
"This is an undervalued source of mortality among vertebrates," said Daniel Rabosky, an evolutionary biologist at the University of Michigan. "A surprising amount of small vertebrate death in the Amazon may be due to arthropods such as large spiders and centipedes."
Once or twice a year, Rabosky leads a team of UM researchers (professors, postdoctors, graduate students and students) and international collaborators on a shipment of more than a month to the Biological Station of Los Amigos in the remote region of Madre of God from Southeast Peru.
The study site, in the lowland Amazon forest near the Andes foot, is at the heart of one of the world's most diverse ecosystems. The main focus of the team's research is the ecology of reptiles and amphibians. But over the years, scientists have witnessed and documented numerous interactions between predatory arthropods and vertebral prey.
"We continue to record these events and, at some point, we learned that we had enough observations to unite them in an article," said Rabosky, associate professor at the Department of Ecology and Evolutionary Biology and associate curator at the UM Museum. Zoology
Spiders are among the predators of arthropods most diverse in the tropics and previous reports of spider predation in the Amazon include the prey of all large vertebrate taxonomic groups: fish, amphibians, reptiles, birds and mammals.
But the knowledge of these interactions remains limited, especially considering the diversity of vertebral prey and predatory potential arthropods in tropical communities rich in species. The new article includes comments from 2008, 2012, 2016 and 2017.
"These events offer a snapshot of the many connections that make up food networks and provide information on an important source of spinal mortality that seems to be less common outside the tropics," said the first author of the study, Rudolf von May, a postdoctoral researcher at the laboratory from Rabosky.
"Where we do this research there are about 85 species of amphibians (mainly frogs and frogs) and about 90 species of reptiles," said von May. "And considering that there are hundreds of invertebrates that can be taken from vertebrates, the number of possible interactions between species is enormous and we are highlighting this fact in this article," said von May.
In addition to the Biological Station of Los Amigos, other observations were made at the Villa Carmen Biological Station, also in the Madre de Dios region of Peru and the Madre Selva Research Station in the Loreto region of northern Peru.
Nearly all sightings were made overnight, when predators of the arthropod are more active. During nighttime surveys, team members walk slowly through the forest with lanterns and headlights, in a single archive, exploring the forest and listening attentively.
During one of the night's inquiries, candidate U-M Michael Grundler and two other students "heard a little scruples in the trash."
"We look back and saw a large tarantula on top of an opossum," said Grundler, co-author of the newspaper. "The oposum had already been understood by the tarantula and was still struggling weakly at that point, but after about 30 seconds he stopped kicking." The tarantula was the size of a plate, and the new fate of the mouse was the size of a softball. Grundler's sister, Maggie, took out her cell phone and shot photos and a video.
Subsequently, an opposition expert at the American Museum of Natural History confirmed that he had captured the first documentation of a large mycorrhiza spider that hurt a hoax. The Mygalomorphae infraorder is a group of heavy weights and heavy legs that include tarantulas.
"We were very stupid and impressed, and we could not really believe what we were selling," said Michael Grundler. "We knew we were witnessing something very special, but we did not know it was the first observation until after the fact."
Most of the prevalent arthropods rely on specialized body parts and poisons to capture and paralyze the vertebral prey. These adaptations include modified jaws, enlarged peaks and massive fangs. Some groups have evolved dozens of poison proteins that are injected during prey capture.
Other predator-prey interactions documented in Conservation of amphibians and reptiles The paper includes:
Several examples of large spiders of the Ctenidae family that predict the frogs and also a lizard. Most predation events documented on the paper involve spiders, and most of these are ctenides, which are commonly referred to as wandering spiders. The Ctenid spiders are predators that hunt at night and wear specialized hairs on the legs to detect aerial vibrations and the direction of prey. Their main eyes are responsible for the discrimination of the objects and the secondary eyes detect the movement.
A large centopebbop of scopopendrid that consumes a Catsby serpent, snail and another cypress eating a dead coral snake that will decapitate. "Coral snakes are very dangerous and can kill humans," said U-M doctoral candidate and co-author Joanna Larson. "To see a demolition by an arthropod was very surprising. These cents are terrifying animals, in fact."
In addition to depredation events, researchers also report infections due to lethal parasites in Amazonian lowland frogs and communal relationships between spiders and frogs. The commensal relation is one that benefits one organism and the other one is not harmed.
"One of the coolest things about working in Peru is the large number of species that are found every day simply walking in the woods," said Larson, who studies the evolution of the diet in the frogs. "Every day you see something new and exciting."
"A branch of the work that we are doing is this collection of strange events of natural history that we witnessed the participation of predators and arthropod vertebrates," he said. "I have not reached the level of being rejected by any of them. We will see that Peru has more to offer."
The other authors of the work, besides Rabosky, von May, Michael Grundler and Larson, are Emanuele Biggi of the International League of Conservation Photographers; Heidy Cárdenas and Roy Santa-Cruz of the Museum of Natural History of the National University of San Agustín, Peru; M. Isabel Diaz of the National University of San Antonio Abbot of Cusco and the Museum of Biodiversity of Peru, both in Peru; Consuelo Alarcón of the John Carroll University and the Biodiversity Museum of Peru; Valia Herrera of the Greater National University of San Marcos, Peru; Francesco Tomasinelli from Milan, Italy; Erin P. Westeen and Maggie R. Grundler from the University of California, Berkeley; Ciara M. Sánchez-Paredes of the Peruvian University Cayetano Heredia, Peru; and Pascal O. Title and Alison R. Davis Rabosky of the U-M Zoology Museum and the Department of Ecology and Evolutionary Biology.
Field research has been supported by a David and Lucille Packard David Rabosky Foundation, as well as the Amazon Conservation Association, the Wildlife Conservation Society, the Rosemary Grant Prize, the Edwin C. Hinsdale UMMZ Scholarship and the University of Michigan.